EDITORIAL

Published: January 5, 2003 7:00PM

With many Cambridge area roads under water, its important to remember that nearly half of all flood-related deaths occur in vehicles. Most of these deaths take place when people drive into flooded highway dips or low drainage areas.

A low-water crossing is where a road, without a bridge, dips across a normally dry creek bed or drainage area. Motorists who attempt to cross these flooded low-water crossings are putting themselves, their vehicles, and any other occupants of their vehicles at deadly risk.

Water weighs about 62.4 pounds per cubic foot and typically flows downstream at 6 to 12 miles an hour, according to the National Weather Service Office of Hydrology. When a vehicle stalls in the water, the water's momentum is transferred to the car.

For each foot the water rises, 500 pounds of lateral force are applied to the car. For each foot the water rises up the side of the car, the car displaces 1,500 pounds of water. In effect, the car weighs 1,500 pounds less for each foot the water rises.

Therefore, most cars will float in just two feet of water.

People who have previously driven successfully through a flooded low-water crossing often do not recognize that an increase of an inch or so in the water level may be all it takes to tip the balance of buoyancy against them.

More than half of all low-water crossing vehicular related deaths occur at night. Under conditions of low-visibility the vulnerability of the driver and passengers to the hidden danger is greatly magnified.